motor and battery recommendations

[lincpimp]

Not a good choice. For 5s lipo use with an xl motor, shoot for around 35k rpm max. You find that by multipling the kv rating by the voltage of the lipo.

So your 6xl would be 2779kv x 18.5v = 51411rpm, that is too much for that motor to handle without getting very hot.

I would say that a 9xl or a 10xl would be a good choice and would run cool in the buggy. I figure that you will be running 40mph or less max speed. The 10xl would most likely give you the best runtime, but require a larger pinion than the 9xl. Both are more than powerful enough to move that buggy, so you can run the motor slower, gear up for speed, and get longer runtimes.

10xl has a 1668kv, and at 18.5v it will turn right at 30k rpm max. Sounds good to me!